Internal grinding machine with automatic air gauge sizing



Feb. 12, 1952 W. J. BRYANT ET AL INTERNAL GRINDING MACHINE WITHAUTOMATIC AIR GAUGE SIZING Filed May 29, 1948 1% 1m m 9, w 23/? 4Sheets-Sheet 1 Feb. 12, 1952 w. J. BRYANT ET AL INTERNAL GRINDINGMACHINE WITH AUTOMATIC AIR GAUGE SIZING Filed May 29, 1948 4Sheets-$heet 2 Feb. 12, 1952 w. J. BRYANT ET AL INTERNAL GRINDINGMACHINE WITH AUTOMATIC AIR GAUGE SIZING Filed May 29, 1948 4Sheets-Sheet 3 fi m/22 1952 w; .1. BRYANT ET AL INTERNAL GRINDINGMACHINE WITH AUTOMATIC AIR GAUGE SIZING Filed May 29, 1948 4Sheets-Sheet 4 3 m u 2% Jw Q 2% W7. w

Patented Feb. 12, 1952 INTERNAL GRINDING MACHINE WITH AUTOMATIC AIRGAUGE SIZING William J. Bryant, Thor H. Ljunggren, and Willis F. Moore,Springfield, Vt., assignors to Bryant Chucking Grinder Company,Springfield, Vt., a corporation of Vermont Application May 29, 1948,Serial No. 29,996

4 Claims.

This invention relates to internal grinding machines with automaticsizing mechanism, and has for an object to provide such a machine wherein the final size control is produced by an air gage sizing mechanism,such a mechanism being capable of extremely high accuracy.

A further object is to embody the air gage in a plug gage mechanismwhich is periodically presented to the work during the finish grindingoperation.

Still another object is to provide a plug air mechanism so constructedas to avoid violent indicator fluctuations with consequent liability todamage during the operation of the machine.

A further object is to provide mechanism by which the grinding operationis stopped the wheel is retracted from the work as soon as the gageindicator shows that the desired finish hole size has been reached.

A further object is to provide for an automatic cycle of machineoperations, the last of which comprises a finish grinding operationwhich is terminated automatically when the desired finished size asdetermined by the air gage been reached.

Further objects and advantages will appear from the followingdescription of an embodiment of the invention shown in the accompanyingdrawings in which Figure l is a front elevation of an internal grindingmachine.

Figure 2 is a fragmentary vertical sectional. view through the workspindle and the work wheel carriage to a larger scale than Figure l andshowing the carriage mounting and the gage stem and its actuating parts,the gage stem being shown as extended within the hole in the work.

Figures 3, 4 and 5 are detail sectional views to a larger scale showingsuccessive rel: in between a work piece, a grinding wheel, air gagestern and related parts as the gr, and traverse of the work by thegrinding wheel progresses, Figure 5 showing the parts after the hole hasbeen ground to a size which permits the gage stem to enter it.

Figure 6 is a detail sectional view on line of Figure 1,

Figure 7 is a diagrammatic sectional view of the air gage mechanism.

Figure 8 is a detail sectional view on line i 3 chine illustrating thecycle control mechanism for gage controlled finish grinding, and eithergage controlled or diamond sizing for rough grinding, the mechanismbeing set for gage controlled rough grinding.

Referring to the drawings, at l is indicated a machine base on which ismounted a traversing carriage 2 which supports a wheel head 3 carrying agrinding wheel spindle 4 upon the outer end of which is mounted agrinding wheel 5. The head 3 is mounted on the carriage 2 for adjustmentbackwardly and forwardly, being supported on ways I in which it is heldby a retaining strip 8 (see Figure 2) held against a foot of the wheelhead, as by screws 9. The traversing carriage 2 carries a bar l0extending in the direction of traverse, and the opposite ends of thisbar are formed hollow as at H (see Figures 2 and 10), thereby providinghydraulic cylinders, within which extend plungers 12 having passages l3therethrough with which communicate fluid pressure pipes l4 and 15. Theplungers i2 are secured in caps 16, which, in turn, are secured to thebed I as by screws 11.

The bed is also provided with transverse 'ways l8 on which is mounted atransversely movable carriage l9 provided with ways 29 for the reception of a work head 2!. The carriage It is shown as supported on rollers22 and is guided along a guide strip 23 against opposite edges of whichbear guide rollers 24 and 25. The specific mounting of this carriage l9forms no part of the present invention, that shown being subject matterof Ljunggren application for patent Serial No. 680,502, filed June 29,1946, for Carriage Mount- The work head 2! has journaled in bearings 28a work spindle 29 having at its forward end a standard spindle nose 3i)and at its rear end a driving pulley 55 by which the spindle may berotated is keyed. To this nose is shown secured by bolts 3|, awork-holding chuck 32 having a plurality of pivoted jaws 33 arranged incircular series about its axis and having fingers 34 at its forward endwhich engage the forward face of a work piece W and hold it pressed backagainst stop pins 35 suitably carried by the chuck 32. This chuck per soalso for-ms no part of the present invention, forming subject matter ofthe Ljunggren and Green Letters Patent No. 2,423,380, granted June 14,1949, for Combination Diaphragm and Clamp Chuck. The jaws 33 are pivotedto a circular flange extending outwardly from a sleeve M which isthreaded to an actuating sleeve 42. By exerting forward axial motion onthe sleeve 42, the jaws 33 may be moved forwardly relative to the bodyof the chuck 32 to a point where they ride out from beneath a cam ring43 so that springs 44 acting on the rear ends of the jaws 33 rock thejaws outwardly, freeing the work piece therefrom. The rear end of thesleeve 42 has journaled nonslidably thereon a ring 53 which is connectedthrough a pin and slot connection at with a lever 52 by the rocking ofwhich the desired axial motion of the sleeve 42 may be effected, thissleeve 42 rotating with the spindle, being keyed thereto as at 53.

Slidable within the sleeve 42 is a tube 60, this tube constituting thestem of an air gage. At its forward end, as shown best on Figures 3, 4and 5, it has a reduced diameter threaded portion 6| with which isengaged a work feeler head 62. This feeler head 52 has an enlargeddiameter outer end portion 63 through which extends a plurality ofradial passages 64 opening out from the periphery of the portion 63. Theinner ends of these passages 84 lead from a chamber 65 opening to theinterior of the tube 60. The feeler head 62 is of such an externaldiameter with respect to the desired finished size of the work that whenit is engaged within the hole in the work, as shown in Figure 5, itpermits discharge of air from the passages 64 past the head 63 and outfrom the hole in the work at a rate such that the air gage indicatorwill show the work to be of the desired finished size.

When the head 52 is out of the work, it is normally housed within abored portion of a sleeve H through which the stem is slidable andwhich, in turn, is slidable axially within the sleeve M. Thecounterbored hole 10 is of a size which receives the head 62, but is notthe same as the desired finished size of the hole in the work so thatthe air gage indicator does not register correct hole size when the head62 is within this counterbored portion.

A size gage of this general type is shown somewhat diagrammatically inFigure 7. The stem 56 is slidable at its rear end within a gland 15 fromwhich it receives air under pressure from a pipe l6. This pipe 16 leadsfrom the upper end of an indicator tube 11, the bore of which is taperedlengthwise, the amount of taper being much exaggerated in the drawings,the upper end of the tube Ti being of the larger diameter.

The lower end of the tube 11 is connected through a pipe 18 with areducing pressure valve 19 which receives compressed air from anysuitable source through a pipe and an air filter 8|.

Within the indicator tube 1! there is an indicator bob 82 which floatsin the air column and the height within this air column at which itrests is determined by the differences in pressure above and beneath it,which in turn, are determined by the freedom with which the airdischarges throug the passages 64, this, in turn, being responsive tothe size of the hole in which. the head 63 is positioned at any time. Avery little difference in diameter of this hole causes a substantialchange in the height position of the bob 82 within the indicator tube11, thus giving 7 a much magnified indication of hole size differences.A spring bumper 85 at the upper end of this tube takes the impacttherefrom in case of a sudden drop in pressure in the pipe 16 whichwould cause the bob 82 to be blown violently upwardly. However, it isundesirable to permit too sudden fluctuations as the bob might bedamaged thereby, and for this reason the sleeve ll has been provided sothat until iii) such time as the hole in the work piece W has beenground to sufficient size to permit the entry of the head 63 thereinto,it remains housed within the counterbored portion 2'0 of the sleeve "H,and when retracted from the hole it passes directly into thiscounterbored portion. This causes the bob 82 to remain suspended in theindicator tube ll, but when the head is in the sleeve, at a positiondifferent from that indicating correct hole size.

During at least the finish grinding portion of the machine cycle, theair gage is in operative condition so that as soon as correct finishedsize is reached, the gage will so indicate it and automatically separatethe wheel from the work and stop the machine cycle. During this finishgrinding, the stem Si is periodically moved toward and from the workpiece in time with the reciprocation of the grinding wheel, being movedtoward the Work as the grinding wheel is retracted and being retractedthe grinding wheel is being projected so as to be out of the way of thegrinding wheel when it extends through the work hole,

as in the position shown in Figure 3. The mechanism for so actuating thestem 60 is best illustrated in Figure 2. This stem 60, as well as allthe other parts carried by the work spindle 29, rotates with the workspindle. The rear end portion of the stem 60 is journaled in bearings 98in a casing 91 which is held against rotation, and to this casing 91 isslidably and pivotally connected the upper arm of a bell crank lever 92fulcrumed on the shaft 53. The other arm 94 of this bell crank lever isconnected through a link 95 to the upper end of a rod 96 guided forvertical motion through a bracket 91 secured to a fixed casing member 58carried by the work head 2|. The lower end of the rod 96 is providedwith a head 95 which is engaged by an actuating rod I00 carried by onearm of a bell crank lever l0! and extended in the direction of motion ofthe carriage l5 so that the head 99 may bear thereon in all positions ofthe carriage l9. This bell crank lever is journaled on the pivot I02carried by a bracket I03 secured to the bed I. Another arm Hi4 of thisbell crank lever IUI engages in the peripheral groove of a spool "15carried by a rod N2, the inner end of which is in position to be struckby the end of the bar in when this bar approaches that end of its strokein which the grinding wheel 5 extends furthest through the work (Figure3), so that as the wheel moves to this extreme position, the rod ismoved to the left, rocking the bell crank lever IZH in a direction tolift the bar 85, which rocks the bell crank lever 94 in a direction toretract the stem 50 out of the way of the grinding wheel. The head 62 ofthis stem engaging the base of the counterbored portions 73 of thesleeve ll also retracts the sleeve 7'! out of contact with the work faceagainst the action of the coil spring IIU which reacts between a head Hiof the sleeve TI and a diaphragm portion H2 of the chuck 32. As thewheel is withdrawn by reverse motion of the bar 19, the rod H26 mayfollow it as far as permitted by a piston portion 25 thereon, riding tothe end of a hydraulic cylinder I21, this piston :20 being carried by asleeve I22 supporting and guiding the rod I03. This allows the rod 96 todrop and allows the spring 1 H] to press the sleeve ii against the workpiece as shown in Figure 4, and if the hole in the work is of sufficientsize, allows the stem to move still further in the same direction toproject the head 6'2 into the work, as shown in Figure 5. When the stemis in accuses the work as shown in Figure 5. the position of the bob 82of the air gage indicates the size of the hole and when this position isat the point corresponding to the desired hole size, the grinding isterminated in a manner which will later appear.

The mechanism for determining the cycle of operations of this machine,including "the control of the final finish grinding operation by the an"gage is a modification of that which forms subject matter in theapplication for patent by Thor H. Ljunggren filed October 5, 1946,Serial No. 701,443 for Internal Grinding Machine which issued as PatentNo. 2,502,862 on April 4, 1950. The mechanism for producing the relativefeed between the work and the grinding wheel as illustrated herein isthe same as that for this Ljunggren application and is shown best inFigures 6, 8, and 9.

The carriage I9 which supports the work hold or is provided with abracket I30 depending from its forward face and secured to the forwardface of the carriage as by screws, one of which is shown at l3I inFigure 6. Journaled in this bracket is the forward end portion of a feedscrew I32. This feed screw is threaded through a circular nut I33 whichis journaled inan upwardly extending flange I34 of the frame I. It isheld against axial movement within a bushing I35 in this frame, and forthis purpose it is provided with a circular end flange I36 between whichand the bushing I35, a collar I31 is interposed, the inner end of thenut I33 being externally threaded for the reception of a nut I36 whichmay bear against a washer I39 interposed between it and the flange 134and the bushing I35. The flange I36 is seated and secured in a socket ina gear I40 and by rotation of this gear I40 it is evident that the leadscrew I32 may be moved axially without its rotation, impartingcorresponding motion to the carriage I9 and the work holder. Suchrotation is made use of to effect the normal feed motion between thegrinding wheel and the work as will later appear.

It is also evident that axial motion of the carriage may be produced byrotation of the feed screw I32 while the nut I33 is stationary; .Suchaction is employed in accordance, with thepresent construction forproducing a slight feed mot-ion of the carriage I9 in addition to thatproduced by rotation of the nut I33 to compensate for reduction of wheelsize due to wear and truing. To this end, the outer end of the feed.screw I32 has keyed thereto the hub I42 of a hand wheel I43,

and secured to this hub is an annular worm gear I44 with which meshes aworm I45 fixed to a shaft I46. As shown in Figure 1, this shaft I46 hasa knob I41 on one end which can be turned by the operator, and it isconnected at its other end to a gear I40 which may be engaged by avertical rack bar I49 carried at theupper end of a plunger I56 (see alsoFigure of a hydraulic cylinder I59. This rack bar is normally heldelevated as by a spring, but may be depressed against this spring, thusto turn the gear I46 when hydraulic fluid is introduced aboveit, asthrough a pipe I4I. A suitable ratchet mechanism (not shown) isinterposed. between the gear I48 and the shaft I46 so that. the liftingof the plunger I58 is ineffective to turn the shaft I46.

The gear I40 is rotated in order to produce the normal feed andretracting motions of the work carriage I9 by the rotation of a. gearI50. meshing therewith, this gear being carried by a hub member I5Iwhich also carries a gear portion I52 with which meshes a rack bar I53.This rack bar I53, as shown diagrammatically in Figure 10, forms thepiston rod for an hydraulic piston I54 riding in a hydraulic cylinderI55. When fluid pressure is introduced to the right hand end of thiscylinder I55 as through the pipe I56, the gear I is rotated in adirection to feed the work relative to the wheel, while when it is movedin the reverse direction by fluid pressure introduced into the left handend of the cylinder I through the pipe I51, the work is retractedrelative to the wheel.

Means are provided by which, after the feed has been started and thework and grinding wheel fed toward each other from fully retractedposition at relatively high speed to a point slightly before the wheeland work contact, the feed motion is slowed, and provision is made bywhich this slowing and the point at which it begins is independentlyadjustable during rough and finish grinding. This mechanism is shownbest in Figures 8 and 9, and diagrammatically on Figure 10. The gear hubI5I has a forward extension I terminating in a reduced diameter portionI6I.

Journaled on this portion I6I are a pair of arms I62 and I63 and keyedto the outer end of the extension I6I is a disk I64. This disk I64 isprovided with a pair of arcuate slots I65 and I66, and the arms I62 andI63 have threaded thereinto the extremities of thumb screws I61 and I68which extend through the slots I65 and I66, respectively, and by thetightening of which the arms I 62 and 63 may be clamped in limitedangular adjustment positions to the disk I64 and be. caused to rock withthe hub extension I60. Each of these arms I62 and I63 has secured to itsrear face a rearwardly extending segmental arm I10 and HI, and each ofthese arms I10 and HI is formed with a thin forward edge which may ridebehind a corresponding switch-actuating roll I12 and I13. When thesearms I10 or I1i engage the switch-actuating rolls I12 or I13, they closeswitches, which, as will later appear, interpose slowing mechanism inthe feed controls,

.so that the speed of feed is reduced and independently for rough andfinish grinding until such time as the feed motion is terminated. Forthe sake of clarity in the diagram (Figure 10), the elements I10 and HIare not shown as arranged about the axis of the gear I50, but insteadare shown as arranged about a second shaft in geared relation to the.gear I50. Either arrangement, of course, may be employed.

With the mechanism herein shown, the feed is terminated for the finishgrinding by the action of the air gage. For the rough grinding it may beterminated selectively either by the impingement of an extension of thepiston. rod I53 (see Figure 10) on a stop I15 carried by an axiallymovable bar I16, this being by diamond sizing, or it may be done by theaction of the air gage. In the diagram of Figure 10 the parts areselectively adjusted for the control of both rough and finish grindingby the action of the gage. The bar I16 is normally pressed, as by aspring I11, into axial position to bring the stop I15 into alinementwith the piston rod. I53, and when in such a-llnement and when struck bythe piston I53 and pressed axially, it closes a switch at I18 which actsto terminate the rough grinding. During finish grinding this bar I16 isplaced in the position shown, by the introduction of hydraulic pressurebeneath its lower end, so that the stop I15 is. in inoperative position.

As hereinabove noted, the wheel supporting 7 carriage 2 is reciprocatedby hydraulic means, this including the hydraulic cylinders formed in theend portions of the bar !0. This reciprocation is controlled by meansshown somewhat diagrammatically in Figure 10. riage 2 are a series ofdepending dogs 260, 20!, and 202. The dog 202 depends further than theothers. The dog 250 is intermediate and the dog 20! is the shortest, andas the wheel carriage is reciprocated these dogs at the end of certainstrokes act upon a follower roll 203 eccentrically carried by the upperend of a control element 204. This control element is rockably mountedand may take three different vertical positions. As shown it is in thehighest of these positions where it is contacted on the inner end of itsstroke by the dog 202 and on the outer end of its stroke b the dog 20!.Such contact causes rocking of the member 204 and this is transmittedthrough a long gear 205 thereon and through a rack 206 to a reversingvalve 201. This reversing valve has a pair of pressure lines 208 and209' leading from a common line 2H2, deriving pressure from a pump 2!!drawing a supply from a suitable tank 2! 2. The pressure delivered bythis pump is controlled by a pressure relief valve 2l3 which dischargesback to the tank 2! 2. In the position shown the valve 20'! openscommunication through the pipe 203 past the valve and the pipe to theright hand cylinder 2!6, thus to drive the carriage 2 to the left, Whilethe discharge takes place from the left hand cylinder through the pipe!4 past the valve 207, through the pipe 220, a valve chamber 22!, past acannelure 222 of this valve chamber 22!, pipe 223, pipe 224 containingan adjustable throttle valve 225, pipe 226, and back to the tank 2!2.Also discharge may take place from the pipe 223 through the valvechamber 22'! around a cannelure 228 of the valve 229, pipe 230 andthrottle valve 23! to the pipe 226. The valves 225 and 23! are thus inparallel and the discharge from these two valves governs the traversespeed of bar !0 during the grinding phase of the work cycle and withvalve 220 in lifted upper position shutting off pipe 230 from pipe 223,the lesser discharge through valve 225 governs the lesser speed of bar!0 during the dressing phase of the work cycle. When the traversecarriage 2 on the bar !0 reaches the point Where the wheel is about toengage the work, a shoe 235 on the carriage engages and closes a switch236, which closes a circuit from a lead 231 to leads 238 and 239 througha solenoid 245] to ground. Energization of this solenoid 243 lifts thevalve 220, closing off the connection from the pipe 223 to pipe 230 sothat discharge through the throttle valve 23! is out 01f, requiring thefull discharge to take place through the valve 225, which thus slows thetraversing motion of the carriage so long as the lead 23'! is suppliedwith energy by means which will later appear.

The length traverse determined by the dogs and 202 is that of thegrinding traverse. The control member 204 may be dropped to anintermediate position where it is contacted by the dog 202, but is notcontacted by the dog 20!. This permits an extended traverse until thedog 200 is contacted which is then effective to reverse the direction oftraverse. takes place at the end of a rough grinding phase of the cycleand during this extended traverse the wheel may be trued as will laterappear.

In the lowest position of the control member 204, the dog 202 isefiective to produce reversal Movable with the car--v This extendedtraverse of the direction of motion at the inner end of the stroke, butthe dog 200 is ineffective to reverse the direction at the outer end ofthe stroke and the wheel carriage comes to rest against a. suitablestop. This action takes place at the end of the grinding cycle,whereupon a finished work piece may be removed from the work holder anda new piece substituted. The operation of the machine is then resumed bythe operator, rocking the control member 204 by hand to again produceits inward stroke.

The control member 204 is moved from one to another of its axialpositions by hydraulic mechanism. To this end the member 204 beneath thecannelure 222 is formed with a socket within which rides the upper endof a piston 245 provided with a vent opening 246 therethrough. Thismember 245 has an enlarged diameter portion 24'! which underlies thelower end of the member 204. When fiuid pressure is admitted through thepipe 248 beneath the portion 241, the piston 245 is pushed upwardly toits upper limit as determined by impingement on the lower end of thecasing of the valve 22! of a stop nut 250. When pressure is admittedbetween the portion 24! and the lower end of the member 204, as throughthe pipe 252, the member 204 is moved to its top position with anenlarged diameter portion 253 at the upper end of the casing 22! Whenpressure is discharged from both of these places, the member 204 is inits lowest position at the end of the grinding cycle, and when fluidpressure is admitted beneath the piston portion 241, and is dischargedfrom between this and the lower end of the member 204, the member 204 isin its intermediate position for extended wheel truing traverse.

The mechanism for controlling admission of fluid under pressure toproduce the various positions of the control member 204 and to controlthe traverse, feed and retracting motions between the wheel and thework, to control the operative or inoperative positioning of the stop!15, the wheel dressing mechanism and the dressing compensator, includeelectrically actuated hydraulic valves A, B, C, D, E, F, G, H, J, and K,and the supply of electric power to determine the positions of thesevalves is controlled by a single control mechanism comprising a shaft260 having thereon a plurality of cams 26la, 26!b, 26Ic, 26!d, 26 !e,together with a rotary cam 262 and an actuating ratchet wheel 263.

The position of the parts shown in Figure 10 is that of the finishgrinding cycle during the relatively slow feed portion prior to thetermination of the cycle and the withdrawal of the wheel slide. In thisposition of the parts the hole in the work has been ground to rough sizeat which the feeler head 62 may enter the hole in the work, as shown inthis figure, when the wheel is sufliciently withdrawn therefrom.Electrical energy is derived from the lines 300 and 30!, the line 300being the grounded side and the line 30! connected through leads 302 and303 to a series of switches 304a, 304b, 3040, 304d, 304a and 3041, whichare adapted to be closed at certain times by suitable cam projections onthe cams 26|a to 26|e and 262. In the position shown, the switches 304dand 304s are closed. The closing of the switch 304d closes a. circuitthrough the leads 305, 306 and the solenoid 30'! to ground, lifting thevalve D. This opens a communication from the pressure pipe 3!0 leadingfrom the pump 2!! through the pipe and passage 3!! and 3!2,respectively, beneath the element I16, thus lifting this element againstthe pressure of the spring I11 and moving the stop I15 out of alinementwith the piston I53, thus conditioning the parts for determining thelimit of grinding not by the extent of feed, but by the air gage, aswill later appear.

The closing of the switch 304s closes a circuit through the leads 3I5,3I6 through the solenoid 3I1 to ground, this lifting the valve E. Thelifting of the valve E opens the pipe I51 from the feed cylinder I55past the valve E through the pipe and passage 3 I 8 past the valve Gthrough the pipe and passage 328, past the valve H, which is now liftedthrough closing of the cycle contact switch 304d, through the passage32I, the throttle valve 322, pipe and passage 323 and discharge pipe 324which leads back to the discharge 226. The throttle valve 322 slows thefeed to the desired point for finish grinding.

The valves G and H are both in lifted position, the valve G liftingsolenoid 338 being energized from the lead 302 through the leads 326,321, switch 328 which has been closed by finish feed cam I10, lead 329,solenoid 330 and to ground. The valve H is energized by the closingofthe switch 304d, through the lead 305 and 306, the solenoid 335 toground. This provides for slow feed, the discharge from the left hand ofthe feed cylinder I55 passing through pipe I51 past 'valve E, throughpipe 3I8, past valves G and H,

through throttle valve 322, and pipe 323 to discharge pipe 324.

The valve K is also in lifted position, this being accomplished by theclosing of the switch 3046 through the leads 305, 3I6, solenoid 331 toground. This admits the pressure from the pressure line 3I0 past thelowered valve J and pipe 338 around the valve K and out through pipe 252beneath the control member 204, and pressure is discharged through thepipe 248 from beneath the piston 241 through the pipe 248 around thevalve J and through the pipe 340 to the discharge pipe 324. The controlmember 204 is thus in its lifted position for actuation by the dogs Iand 202, which is thus in condition for the short grinding stroke of thecarriage.

This condition takes place with the air gage stem entering the work oneach retraction of the wheel therefrom until such time as the indicatorbob 82 takes a position indicating the correct hole size at which itinterrupts light from a light sources 350 from falling upon aphoto-electric call 352. The light source 350 is energized from thesecondary 353 of a transformer, the primary 354 of which is positionedacross the lines 300 and I the current passing from the secondary 353through lead I, switch arm 356, lead 351, lamp 350, lead 358, back tothe transformer secondary held closed by the energization of the relay359 from lead 3590, switch 2000, lead 306 and closed cycle switch 304dand lead 303. As long as light passes from the source 350 to thephoto-cell 352, current flows from rectifier 3'6I fed from thetransformer primary 354 through a resistor 360 in series with the cell352. This current is derived from the leads 300 and 30I through aconventional half wave rectifier, indicated at 36I, from which leads36.2 and 363 pass to the resistor 360 and to one terminal of thephoto-cell 352, a lead 364 connecting the other side of the phototube tothe resistor 3600. While current so passes, a negative bias is obtainedfrom the resistor 360 and passes through the leads 365, 366 and 361 tothe grid of the gas filled "thyratron tube 310, which blocks the anodedischar 31I from passing current through the relay 312, one side ofwhich is connected thereto through the lead 313. The other side isconnected through lead 314 through normally closed switch 315 and lead316 to a variable resistor 321, one end of which is connected throughthe lead 318 with the rectifier 355 which derives energy across thelines 303 and 30I from the transformer 380.

As soon as the bob 8 2 interrupts the light passing to the photo-cell,the photo-cell passes less current and after a small time delayeffective to prevent momentary cutting off this light from actuating themechanism, the negative bias on the grid of the thyratron 310 is reducedto a magnitude which allows passage of plate current and energizes therelay 312. This time delay, as shown, is afforded by the resistor 360with capacity 3650 inparallel therewith. Closing of the relay 312 closesa switch 38I, which through a lead 382 is connected to solenoid 383.Energization of this solenoid 383 steps around the cycle changemechanism by acting on the ratchet wheel 263. This closes the switch304i by the cam 262 to the lead 384 through the ratchet solenoid 333,

. impressing a secondary turning impulse to the shaft 280 and insuring aone-eighth rotation of this shaft at each actuation. This turn of theratchetwheel opens the cycle switches 304d and 304e and closes theswitch 3046;, all the other cycle switches being open. The cyclemechanism is then in load angular position. Opening of the switch 304ddeenergizes the relay 359 and extinguishes the lamp 350 since it allowsthe switch arm 356 to swing over, breaking contact with the lead 351 andmaking contact with the lead 385. The making of this contact with thelead 385 lights a second lamp 390 positioned beneath the lamp 350 andshielded therefrom by a partition 3 9I placed between them. Theenergization of the lamp 390 is from the transformer secondary 353through lead 35I, switch 356, lead 385, lamp 390, lead 358 and back tothe transformer secondary 353. The lamp 390' shines through atranslucent window in the sides of the gage tube 1 1 beneath the Windowthrough which the lamp lead 366 to thesolenoid392 and to ground.Energization .ofthe solenoid 392 lifts the valve A and allows fluidunder pressure from the pressure pipe 31 0; to fiow through the pipe393to the right hand end of the cylinder .I'2-l, driving its piston I22 tothe left so retracting the air gage from the work. Opening of the switch304e deenergizes the solenoid 331, allowing the valve K to fall, whichopens the pipe 252 to discharge. The valve 304C being open, valveJ isalso in the lowest position, opening pipe 240 to discharge. This allowsthe control member 204 to drop to its lowest position.

Opening of the switch 304e deenergizes the solenoid 3I1, allowing thevalves E and F to drop, opening up'the left end of the feed cylinder Ito The wheel carriage 2 thus fully retracts to loading position and thecarriage I9 to fully retracted feed position, and since the memher 204is notautomatically rockedtc reverse the. traverse, the wheel carriagestops in fully retracted position-against a suitable stop. The closing 1l of the switch 304a also energizes the cycle start switch 4I0 throughthe lead 4| I so that when the switch M0 is closed in the next cycle ofoperations, the cycle control mechanism will be stepped along by afurther one-eighth turn.

To start the cycle, the operator rocks the member 204, which at thismoment is in its lowermost vertical position, allowing discharge at thefast rate from left end cylinder II, pipe I4, valve 201, pipe 220,cannelure 222, pipe 2230, pipe 226, to tank 2I2. The rocking of member204 effects a reversal of the direction of traverse so that the wheelcarriage starts at a fast speed 'rate toward the Work, and as soon asthe switch 4I0 is closed by contact with the inclined face of the dog 4|5 on the carriage, the ratchet solenoid 383 is energized through thelead 4I6 and the cycle control is stepped around to its second or roughgrinding position in which switches 3041) and 3048 are closed, andswitch 304a is opened. Closing of the switch 304e energizes the lead 3I6and solenoid 3I1, lifting the valves E and F, opening fluid pressure tothe right hand end of the feed cylinder and discharge from the left end,but under a fast rate. Energization of the lead 3I6 also energizessolenoid 331, lifting the valve K, which introduces fluid pressurebeneath the valve 22I, lifting the control member 204 to its highestposition for working traverse.

Before the wheel contacts the work in feed direction, the cam I12 hasbeen rotated sufficiently to close the switch I120, which closes acircuit through the cycle switch 304b, leads 420 and 42I, switch I120,lead 329 and solenoid 330. This raises the valve G, which interposes thethrottle valve 3220 in the discharge from the feed cylinder, the valvel-I being now lowered, cutting out the throttle valve 322.

The lower lamp 390 being now lighted and the gage being reciprocated intime with the wheel (the clinder I2| being discharged through pipe 393past lowered valve B), the gage enters the hole in the work before thecompletion of the rough grinding which is terminated when the bob 82shuts off light to the cell 352 from the lamp 390.

This, as before noted in connection with the finish grinding phase ofthe cycle, closes the switch 382 which steps the cycle control mechanismoneeighth of a turn to the dressing step of the cycle.

In this step, switches 304a and 3040 are closed.

Closing of the switch 304a completes the circuit through the switch 3000and lead 396 to the solenoid 392, lifting the valve A, introducing fluidpressure through the pipe 393 to the right of the gage, retractingcylinder I2I which retracts the gage. It also energizes the relay 4I2through the lead M3 and opens the switch 315 in the anode circuit of thethyratron 310. It also energizes the lead 4|I leading to the carriageoperated switch 4I0, but on the retracting stroke of the carriage, thedog 4| 5 yields so that the switch 4| 0 is not operated. Closing of theswitch 3040 energizes the lead 425, which through lead 426, energizesthe solenoid 402 and lifts the valve J. This introduces fluid pressurethrough the pipe 248 beneath the piston 245, and as the solenoid 331 hasbeen deenergized, the pipe 252 is open to discharge so that the controlmember 204 takes its intermediate position, extending the traverse. Whenthe carriage closes the switch 236, the solenoid 240 is energized fromlead 303, closed smitch 304e, lead 231, switch 236 and leads 238 and 239and solenoid 240, lifting the valve 229, and slowing the traversethrough the dressing throttle valve 225 only, and the valve B is liftedof this cylinder to discharge through the pipe H36,

and as soon as the retraction is complete the double switch arm 391closes connection from lead 40I to lead 403. This establishes a circuitfrom lead 303, closed cycle switch 3040, leads 425, and

426, MI, 403 and solenoid 404. This lifts valve C which allows fluidunder pressure to pass this valve through pipe |4I into the compensatorcylinder I59, which produces the additional feed increment whichcompensates for wheel wear and truing. When cycle switch 3040 opens onthe succeeding cycle control mechanism actuation, the valve C drops andpasses discharge from the compensator cylinder, which returns thecompensator feed to starting position. On the return traverse of thecarriage, its stroke being reversed by turning of the member 204 byimpingement by the dog 260, the switch M0 is closed by the dog 4I5,energizing the ratchet solenoid 383 and. stepping the cycle mechanism afurther one-eighth turn to finish grinding condition shown in Figure 10.

When diamond rough sizing rather than air gage rough sizing control isdesired, the switches 2000 and 3000 are placed in their dotted lineposition. These switches are effective only in the rough grindingportion of the cycle when switch 304D and 3046 are closed and the othercycle control switches are open. The closing of the switch 3000 to theswitch 304b energizes the lead 396 and the solenoid 392, lifting thevalve A, which causes fluid pressure to enter the right hand end of thecylinder I2 I' and retract the air gage. Closing the switch 3041) alsoenergizes the relay 4| 2 and opens switch 315 and makes it possible forthe thyratron tube to recover to the condition it had before the earlierimpulse from a cell 352 caused the relay 312 to be energized. Closingthe switch 2000 to the lead 302 energizes the relay 359 and causes theswitch 356 to energize the finish grinding lamp 350. The valve D beinglowered in this position of the cycle, the stop I15 is in line with thepiston I53 so that rough grinding continues, first at a fast rate andthen at a slower rate when the cam |1| closes the switch I120, until thepiston I53 strikes the stop I15 and closes the switch I18. This closes acircuit from the lead 302 through a time delay, lead 435, switch I18,leads 436, 4360, and 392 to the ratchet solenoid 393 which then acts tostep the cycle control mechaw nism to its truing position. The cycle maythus selectively control the rough grinding either by the air gage or byso-called diamond sizing, the latter depending upon the feeding limitduring the rough grinding operation.

From the foregoing description of certain embodiments of this invention,it should be evident to those skilled in the art that various changesand modifications might be made without departing from its spirit orscope.

We claim:

1. In combination in a hole grinding machine, an air gage having a sizeindicator and a tubular stem provided at one end with a work feelerportion of enlarged diameter, said feeler portion having an airdischarge opening through its periphery, a sleeve slidably surroundingsaid stem and having a counterbored end portion adapted at certain timesto house said ieeler portion and of an internal diameter slightlydifferent from the desired finished size of a hole in a work piece sothat when said feeler is within said sleeve said indicator is out ofdesired finish size indi cating position, means supporting a Work piecewith a hole coaxial with said stein, a grinding wheel, means forrotating said wheel, means for relatively reciprocating said wheel andwork axially, means for relatively feeding said wheel and worktransverse to said axis, means acting in time with such reciprocation topress said stem and sleeve toward the work to enter the hole beingground .therein when said hole hecomes oi' sufficient size to receivesaid stem at which time said discharge orifice leaves said sleeve andenters the work whereupon said indicator indicates the hole size, acycle control mechanism, and means actuated and controlled by saidindicator when said indicator indicates the desired hole size to actuatesaid mechanism to effect the succeeding step in the cycle of themachine.

2. An internal grinding machine comprising a rotary work spindle, meansfor supporting work with a hole to be ground coaxial with said spindle,a rotary grinding wheel, means for relatively moving said spindle andwheel lengthwise of said axis to cause said wheel to traverse the workand to have an extended traverse to separate said Wheel and work fromeach other, an air gage having a stem provided with a lateral orificeadapted to enter the hole in the work after such hole has been ground tonearly finished size, means acting in time with the relative traversebetween the work and grinding wheel to present said stem to the work toenter therein when the hole is of sufficient size, a wheel truing devicemovable to and from a position to true the wheel during an extendedtraverse, means for producing a relative feed between the work and wheellaterally of the direction of traverse, a single control mechanism,means actuated at a predetermined feed position corresponding totermination of a rough grinding operation between said wheel and work tocondition said control mechanism to effect extended traverse with wheeltruing and then to resume grinding and feed, and means actuated by saidair gage when said stem orifice enters the hole in the work and whensaid hole reaches desired finish size to efiect extended traverse toseparate the wheel from the work and to then terminate the cycle.

3. An internal grinding machine, comprising a work holder, a grindingwheel, means for relatively moving said wheel and holder to cause saidwheel to grind a hole in work carried by said holder, a hole size gageprojectable into said hole when said hole is of suilicient size to admitit and including an upright column, means for alternately projecting andretracting said gage, a bob movable within said column and assuming aposition therein corresponding to the hole size when said gage is inprojected position, a cycle control mechanism determining a sequence ofoperations of a grinding cycle, and mechanism responsive to twopositions of said bob in said column, in one position corresponding toroughing hole size and in the other position corresponding to finishhole size, to move said cycle control mechanism to the next controllingposition in the cycle sequence.

4. An internal grinding machine, comprising a work holder, a grindingwheel, means for relatively moving said wheel and holder to cause saidwheel to grind a hole in work carried by said holder, ahole size gageprojectable into said hole when said hole is of sufficient size to admitit and including an upright column, means for alternately projecting andretracting said gage, a bob movable within said column and assuming aposition therein corresponding to the hole size when said gage is inprojected position, a cycle control mechanism determining a sequence ofoperations of a grinding cycle, means for projecting light beams acrosssaid column at either of two lengthwise positions one corresponding to aposition of said bob corresponding to rough grinding size and the otherto a position of said bob corresponding to finish size, and meansresponsive to the interruption of one and then the other of said lightbeams for moving said cycle control mechanism to the next followingposition.

WILLIAM J. BRYANT. THOR H. LJUNGGREN. WILLIS F. MOORE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,817,953 Stevens Aug. 11, 19311,862,215 Gallimore June 7, 1932 1,927,750 Mennesson Sept. 19, 19332,001,447 Balsiger May 14, 1935 2,010,706 Williams Aug. 6, 19352,050,261 Blood Aug. 11, 1936 2,465,035 Polk et a1. Mar. 22, 19492,471,737 Fox May 31, 1949

